This is the 1930th most frequent Turkish word.
kaçan
"Kaçan" means "escaping" or "runaway."
In this sentence, "kaçan" is used as a participle describing the student who missed the opportunity.
Fırsatı kaçan öğrenci üzgün görünüyordu.
The student who missed the opportunity seemed sad.
Here, "kaçan" is used metaphorically for 'escaping' to describe the fish that slipped away.
Kaçan balık büyük olur, derler.
They say that the fish that got away is always big.
In this context, "kaçan" is used to describe the bus that escapes or leaves before the person can get on.